1. Field of Invention
The present invention relates to a positive displacement pump in which the capacity in a pump chamber is changed with a piston, a diaphragm or other device to move fluid. More specifically, the invention relates to a reliable pump with high flow rate.
2. Description of Related Art
Such related art pumps have an arrangement in which check valves are disposed between a suction channel and a discharge channel. A pump chamber is provided that has a capacity that can be varied. Such a pump is disclosed in Japanese Unexamined Patent Application Publication No. 10-220357 (JP 357).
The related art also includes an arrangement of a pump to produce one-directional flow using viscous resistance of fluid, which has a valve in the discharge channel. When the valve is opened, the suction channel has higher fluid resistance than the discharge channel. Such a pump is disclosed in Japanese Unexamined Patent Application Publication No. 08-312537 (JP 537).
In order to enhance the reliability of a pump, the related art provides a pump with an arrangement in which a mounting part is not provided and in which both the suction channel and the discharge channel have a compression component having a channel shape in which pressure drop varies depending on the direction of the flow. Such a pump is disclosed in PCT Japanese Translation Patent Publication No. 08-506874 (JP 874), and Anders Olsson, An improved valve-less pump fabricate using deep reactive ion etching, 1996 IEEE 9th International Workshop on Micro Electro Mechanical Systems, pgs. 479–484 (Olsson).